1. Field of the Invention
The invention relates to a bobbin for an electromagnetic inductive coil and in particular to such a coil bobbin used with a ferromagnetic core.
2. Discussion of the Prior Art
As shown in FIG. 1A, there is known a coil bobbin 10 molded from a plastic or resin-type material. At adjacent rounded corners 12 and 14 of the bobbin 10, there is a first electrical contact terminal 16 and a second electrical terminal 18, mounted to the corners 12 and 14, respectively. These terminals 16 and 18 are usually secured by either soldering or rivets or compressed first and second eyelets 20 and 22, also known as grommets.
As seen in FIG. 1B, the first terminal 16 of the bobbin 10 connects via the eyelet 20 to a so-called start wire 24. Returning to FIG. 1A, the start wire 24 is located at a beginning of a wire coil 26 that wraps around a hollow body 28 of the bobbin 10. The coil 26 has located at its end a so-called finish wire 30 which connects via the second eyelet 22 to the second terminal 18.
During the course of a preliminary patentability search for molded plastic or resin-type coil bobbins having terminals secured thereto, exemplary prior art references were located.
For example, U.S. Reissue Pat. No. 16,854 (originally U.S. Pat. No. 1,612,947) was granted on Jan. 17, 1928, to Schermerhorn for a transformer securing electrical terminals 22 thereto via riveted eyelets 21. In particular, see FIGS. 1 and 3 of Schermerhorn.
U.S. Pat. No. 3,068,435 was obtained by Oliver Jr., et al. on Dec. 11, 1962, for an electromagnetic coil having connections 13 to tabs 14 secured by rivets 15 to a bobbin held by a core 18. In particular, see FIGS. 4 and 5 of Oliver Jr., et al.
U.S. Pat. No. 3,605,055 was issued to Grady on Sep. 14, 1971, for a winding bobbin 1 for coils 151 and 171. Pockets 20 and 21 support contacts 18 and 19, respectively. In particular, see FIG. 3 of Grady.
U.K. Patent Application No. 2,108,769 of Suzuki was published on May 18, 1983, for an arrangement of electrodes 9 within notched portions (unnumbered) of a flange 6 on a drum (unnumbered) around which a wire coil 10 is wrapped. In particular, see FIG. 5 of Suzuki.
However, in the prior art bobbin 10 illustrated in FIG. 1A, if a rotational force F1 or F2 is applied to either the terminal 16 or the terminal 18 or both, the bobbin 10 will rotate or one of the terminals 16 and 18 will snap off due to breakage at one of the eyelets 20 and 22 or one of two plastic side flanges 32 and 34 will fracture at the corner 12 or 14.
Thus, it remains a problem in the prior art to support securely the terminals attached to the coil bobbin in order to prevent rotation of the bobbin whenever a rotational force is applied to a terminal.